There is no reason to restrict the use of computers to the
simulation of physically accurate lighting. Indeed it has been
recognized in recent years that computer processing
opens fascinating new avenues for rendering images that convey
particular views, emphasis, or style. These approaches are often
referred to as "non-photorealistic rendering", although I prefer the
term "expressive rendering" to this negative definition.

A part of computer graphics can be viewed as a visual communication
tool. Such a point of view implies several goals that we target with
expressive rendering. In particular the user of an
expressive rendering tool should be able to produce the images that
corresponds to his own goals.

This involves, in particular, significant work on the notion of relevance,
which is necessarily application-dependent. The relevance should guide
the level of abstraction of the rendered scene to let the user
emphasize the most important elements of the input 3d scene. It can
also be defined from a levels-of-detail point of view: not only can we
adapt the geometry to decrease the computation time, but we can also
adapt the rendering style to meet the user's goals.

Another research direction for expressive rendering concerns rendering
styles: in many cases it should be possible to define the
constitutive elements of styles, allowing the application of a given
rendering style to different scenes, or in the long term the capture of
style elements from collections of images.

Finally, since the application of expressive rendering techniques
generally amounts to a visual simplification, or abstraction, of the
scene, particular care must be taken to make the resulting images
consistent over time, for interactive or animated imagery. This leads
to various projects targeting the temporal coherence of animated scenes.

The ARC INRIA project ARCHEOS
has been a first attempt to work with archaelogists. This project was targeting a virtual immersion
in the ancient Greek city of Argos.
The ARC INRIA MIRO
continued the collaboration with archaeologists adressing the problem
of producing legible renderings.

Work with studio productions has been conducted with Studio Broceliande and in the context
of the ANR Animare.
These projects aim at creating renderings tools for digital artists.